.. PRTG Manual: QoS (Quality of Service) One Way Sensor

The QoS (Quality of Service) One Way sensor monitors parameters regarding the quality of a network connection between two probes. This is important, for example, when using Voice over IP (VoIP) over this connection.

The sensor sends a series of User Datagram Protocol (UDP) packets from the parent probe to a different probe and measures these parameters:

You have to configure at least one remote probe in your PRTG on premises setup for this sensor to work, and at least two remote probes in PRTG hosted by Paessler.

You can create this sensor on the probe device of a local probe or a remote probe.

You cannot add this sensor to the hosted probe of a PRTG hosted by Paessler instance. If you want to use this sensor, add it to a remote probe device.

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the setting fields that are required for creating the sensor. Therefore, you do not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.

Sensor Settings

Click the Settings tab of a sensor to change its settings.

Usually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.

Enter one or more tags, separated by spaces or commas. You can use tags to group sensors and use tag–filtered views later on. Tags are not case sensitive. We recommend that you use the default value.

There are default tags that are automatically predefined in a sensor's settings when you add a sensor. See section Default Tags below.

You can add additional tags to the sensor if you like. Other tags are automatically inherited from objects further up in the device tree. These are visible above as Parent Tags.

It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

Priority

Select a priority for the sensor. This setting determines where the sensor is placed in sensor lists. A sensor with a top priority is at the top of a list. Choose from one star (low priority) to five stars (top priority).

Default Tags

qossensor

Quality of Service Measurement

Timeout (Sec.)

Enter a timeout in seconds for the request. If the reply takes longer than this value, the sensor cancels the request and shows a corresponding error message. Enter an integer value. The maximum value is 900 seconds (15 minutes).

Target Probe

Define the target probe that receives the UDP packets. The dropdown menu shows all local probes and remote probes in your setup.

When running the sensor on the local probe, select a remote probe as the Target Probe. If no remote probe is available, install and connect a remote probe first. When running the sensor on a remote probe, select either a different remote probe or the local probe in as target. The sensor measures values for the network track between the parent probe and the target probe.

You must ensure that firewalls or network address translation (NAT) rules allow UDP packets to reach the target probe. The Windows firewall on the target system is automatically opened by the probe.

In PRTG hosted by Paessler, you can only select a different remote probe as the target probe. QoS measurements for connections to the hosted probe are not possible.

Target Host/IP

Define the IP address of the target probe to which the parent probe connects. If you do not use NAT rules, this is usually the address shown above (next to the target probe's name).

Port

Define the source and target port for the UDP packets. This port is used on both the source probe and the target probe. Use a different port for each QoS sensor to make sure that packets can be assigned correctly. Enter an integer value between 1024 and 65536.

This port must be available on both the source system and the target system.

Number of Packets

Define how many packets the sensor sends with each scanning interval. Enter an integer value. The default value is 1000.We recommend that you use the default value.

Size of Packets (Bytes)

Define the size of the packets in bytes that the sensor sends. Enter an integer value. The default value is 172.We recommend that you use the default value.

Time between Packets (ms)

Define the time in milliseconds that the sensor waits between two packets. Enter an integer value. The default value is 20.We recommend that you use the default value.

Sensor Display

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking the pin symbol of a channel on the sensor's Overview tab.

Graph Type

Define how different channels are shown for this sensor:

Show channels independently (default): Show a graph for each channel.

Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.This option cannot be used in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This field is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Inherited Settings

By default, all of the following settings are inherited from objects that are higher in the hierarchy and should be changed there if necessary. Often, best practice is to change them centrally in the Root group's settings. For more information, see section Inheritance of Settings. To change a setting for this object only, disable inheritance by clicking the button next to inherit from under the corresponding setting name. You then see the options described below.

Select a scanning interval (seconds, minutes, or hours). The scanning interval determines the amount of time that the sensor waits between two scans. You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Define the number of scanning intervals that the sensor has time to reach and check a device again in case a sensor query fails. Depending on the option that you select, the sensor can try to reach and check a device again several times before the sensor shows a Downstatus. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows a Warning status. Choose from:

Set sensor to down immediately: Set the sensor to a Down status immediately after the first failed request.

Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to a Warning status after the first failed request. If the following request also fails, the sensor shows an error.

Set sensor to warning for 2 intervals, then set to down: Set the sensor to a Down status only after three consecutively failed requests.

Set sensor to warning for 3 intervals, then set to down: Set the sensor to a Down status only after four consecutively failed requests.

Set sensor to warning for 4 intervals, then set to down: Set the sensor to a Down status only after five consecutively failed requests.

Set sensor to warning for 5 intervals, then set to down: Set the sensor to a Down status only after six consecutively failed requests.

Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show a Down status. It is not possible to immediately set a WMI sensor to a Down status, so the first option does not apply to these sensors. All other options can apply.

If you define error limits for a sensor's channels, the sensor immediately shows a Down status. No "wait" option applies.

If a channel uses lookup values, the sensor immediately shows a Down status. No "wait" options apply.

Schedules, Dependencies, and Maintenance Window

You cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional settings here. They are active at the same time as the parent objects' settings.

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days or hours) every week.

You can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Account Settings—Schedules.

Schedules are generally inherited. New schedules are added to existing schedules, so all schedules are active at the same time.

Maintenance Window

Specify if you want to set up a one-time maintenance window. During a maintenance window, the current object and all child objects are not monitored. They are in a Pausedstatus instead. Choose between:

Not set (monitor continuously): No maintenance window is set and monitoring is always active.

Set up a one-time maintenance window: Pause monitoring within a maintenance window. You can define a time span for a monitoring pause below and change it even for a currently running maintenance window.

To terminate a current maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

Maintenance Begins

This field is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the maintenance window.

Maintenance Ends

This field is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the end date and time of the maintenance window.

Dependency Type

Define a dependency type. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:

Use parent: Use the dependency type of the parent object.

Select a sensor: Use the dependency type of the parent object. Additionally, pause the current object if a specific sensor is in a Down status or in a Paused status caused by another dependency.

Master sensor for parent: Make this sensor the master object for its parent device. The sensor influences the behavior of its parent device: If the sensor is in a Down status, the device is paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor is paused if the parent group is paused by another dependency.

To test your dependencies, select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects are paused. You can check all dependencies under Devices | Dependencies in the main menu bar.

Dependency

This field is only visible if you enable Select a sensor above. Click the Search button and use the object selector to select a sensor on which the current object will depend.

Dependency Delay (Sec.)

This field is only visible if you enable Select a sensor above. Define a time span in seconds for dependency delay.

After the master sensor for this dependency comes back to an Up status, monitoring of the dependent objects is additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Enter an integer value.

This setting is not available if you set this sensor to Use parent or to be the Master sensor for parent. In this case, define delays in the parent device settings or in its parent group settings.

Define the user groups that have access to the selected object. A table with user groups and types of access rights is shown. It contains all user groups from your setup. For each user group, you can choose from the following access rights:

Inherited: Use the access rights settings of the parent object.

None: Users in this group cannot see or edit the object. The object neither shows up in lists nor in the device tree. Exception: If a child object is visible to the user, the object is visible in the device tree but it cannot be accessed.

Read: Users in this group can see the object and review its monitoring results.

Write: Users in this group can see the object, review its monitoring results, and edit its settings. They cannot edit access rights settings.

Full: Users in this group can see the object, review its monitoring results, edit its settings, and edit access rights settings.

You can create new user groups in the System Administration—User Groups settings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option.

To change display settings, spike filtering, and limits, switch to the sensor's Overview tab and click the gear icon of a specific channel. For detailed information, see section Sensor Channel Settings.